1. The Field of the Invention
The present invention pertains to a method and apparatus utilizing a static mixing system and check valves to perform acceptable levels of mixing of fluids over wide ranges of flow rates without experiencing excessive pressure drops.
2. The Prior Art
In many industries there is a need for mixers to mix fluids such as liquid/liquid, gas/liquid, and liquid/solids. Static mixing systems generally defined as mixing systems without driven parts, are often used as an energy efficient way of effecting the desired mixing. The general operating principle for the prior art static mixing systems is to have the pressure from the fluid stream converted to shear and turbulence which will cut the entrained bubbles or droplets more finely and mix the dispersed phase more homogeneously. The design of static mixing systems can vary greatly from orifices and constricted piping to various pipe insertions that cause the fluid to twist and turn creating internal eddies and back mixing. For effective mixing, most static mixing systems require a minimum pressure drop of 1 to 3 psi across them. Since the fluids are in turbulent flow regime, the pressure drop across the mixer is proportional to the square of the flow rate. Turndown ratios are necessarily low as the pressure drop increases rapidly with flow. For example, a mixer having a pressure drop of 1 psi at the low end would have a pressure drop of 100 psi when the flow rate is increased ten times.
In the petroleum industry there is a particular need to provide well-mixed fluids prior to gas/liquid and liquid/liquid sampling and/or metering. Unfortunately, the liquid and gas flows to be sampled and/or metered can vary greatly from well to well and even the flow from a single well can vary from time to time thereby making the know static mixing systems less than suitable for mixing sufficiently to achieve the desired accuracy.